The European drugs regulator has recommended lifting the suspension on Bayer's heart-surgery drug Trasylol, saying the results of a study that led to its being taken off the market were unreliable. Trasylol, based on the active ingredient aprotinin, prevents excessive blood loss during surgery by halting the breakdown of fibrin, a protein found in blood clots. The drug had been widely used since the 1990s during heart bypass surgery. Bayer pulled the drug globally in November 2007, after preliminary results of a Canadian study known as BART appeared to show an increased death rate in patients 30 days after taking the medicine.